Hello Charles and MMD,  Regarding the control linkage in a Standard
player action:  If nothing is missing, you may be able to figure it out
by analyzing each operation (tempo control for instance) and observing
how the motion of the lever in the key slip could use the parts there
under the key bed to move the roll governor tempo slide and the crank
and rods that move the tempo indicator in the spool box.  

This sort of "Forensic investigation" is actually a lot of fun.  If
parts are missing, the sketches and description provided by someone
who's done it before will be helpful.
 
By solving the simple mysteries first, it becomes easier to resolve 
the difficult issues because there are fewer remaining unknowns.
Remember that sometimes there is more than one way an operation can 
be accomplished.  If the wrong choice uses parts or connection points
needed by another operation, look for the other possible ways to
accomplish it that will free up the required elements.
 
Bob Hunt
Kennebunk, Maine